Are you talking about the AdventureCraft mod by Cryect? That's been dead for some time now, so the engine can no longer pull maps from the original location.
Try downloading them directly from the links on the archived site:
I just downloaded the Zelda Adventure v0.9.7 map from the given mediafire link, if you want it;
http://www.mediafire.com/download/17cw2p2dmndlrl6/Zelda Adventure V0.9.7.zip